Field of the Invention
The present invention relates to fuel apparatus for vehicles, and more particularly, to a fuel apparatus capable of restraining evaporation gas from leaking from within a sealed fuel tank to outside.
Description of the Related Art
In order to restrain evaporation gas in a fuel tank from being released into the atmosphere, a fuel apparatus for a vehicle, especially a fuel apparatus for a hybrid vehicle which is equipped with the combination of a traveling motor and an engine and in which the engine is less frequently operated employs a sealing system for sealing the interior of the fuel tank, to prevent the evaporation gas from leaking to the outside of the fuel tank.
In such sealing system, the evaporation gas in the fuel tank is disposed of (burned) by the engine while the engine is operating. Since the evaporation gas generated during refueling cannot be disposed of during refueling, however, the fuel apparatus with the sealing system includes a dedicated canister (for exclusive use during refueling), a vapor passage connecting the fuel tank and the canister, and a normally closed sealing valve for opening and closing the vapor passage. In normal condition, the sealing valve is closed to seal the interior of the fuel tank, and during refueling, the sealing valve is opened to guide the evaporation gas in the fuel tank to the canister, thereby allowing the evaporation gas to be adsorbed by the canister and preventing the evaporation gas from being released into the atmosphere from the filler port of the fuel tank (cf. Japanese Unexamined Patent Publication No. 2013-19281). The canister is purged during operation of the engine in a manner such that the evaporation gas adsorbed by the canister is guided to the intake side of the engine.
Also, for the purpose of management of the fuel tank, the fuel apparatus detects leak of the evaporation gas from the fuel tank in the sealed state.
For example, in the aforementioned patent publication, a leak detection portion including a pressure sensor for detecting the pressure in the fuel tank and a control unit is used to determine whether or not the evaporation gas is leaking from the closed space in the fuel tank (closed space including the space in the fuel tank above the level of the fuel, a passage portion closed with the sealing valve and a passage portion up to the filler port closed with a fuel cap), at an appropriate time (at predetermined intervals of time, e.g. at intervals of five hours) while the ignition switch (IG) is on or while the ignition switch is off, for example, while the vehicle is parked with no occupants therein. If it is judged that the evaporation gas is leaking, the driver is notified of the leak by, for example, an indicator on the instrument panel of the vehicle, thereby urging the driver to take appropriate measures.
The sealing valve remains closed after detection of leak of the evaporation gas from within the fuel tank is completed, and accordingly, if the evaporation gas is actually leaking from a certain spot, it keeps leaking from the leaky spot without being guided to the canister. Thus, while the vehicle is parked, for example, all of the evaporation gas in the fuel tank may possibly be released into the atmosphere without being noticed by the driver.